SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '186ebe0b2d67067cc12fa4e60d847122dc1b6ee70342373afa6664086ddc646c' 
  AND token = 'MQfxMx7H83yzqNt8o5FYR6AuXycvlMXD3gxhODys6iE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}